Sections considered

AS/NZS 4600:2018 Cold-formed steel structures

SECTION 1 SCOPE AND GENERAL

1.1 SCOPE (thickness)

1.3 DEFINITIONS

1.3.5 Bend

1.5 MATERIALS

1.5.1.4 Ductility (fu/fy ratio)

1.6 DESIGN REQUIREMENTS

1.6.3(a) Design capacity

Table 1.6 (b),(c),(d),(e),(f)

SECTION 2 ELEMENTS

2.1 SECTION PROPERTIES

2.1.1 General

2.1.2 Design procedures

2.1.2.1 Full section properties

2.1.2.2 Effective section properties

(b) local instabilities

2.1.3 Dimensional limits

2.1.3.1 Maximum flat-width-to-thickness ratios

(a)(i),(b),(c)

2.1.3.4 Maximum web depth-to-thickness ratio

(a) unreinforced webs

2.2 EFFECTIVE WIDTHS OF STIFFENED ELEMENTS

2.2.1 Uniformly compressed stiffened elements

2.2.1.1 General

2.2.1.2 Effective width for capacity calculations

(a),(c),(i),(ii)

2.2.1.3 Effective width for deflection calculations

(a) Procedure I

2.2.3 Stiffened elements with stress gradient

2.2.3.1 General

2.2.3.2 Effective width for capacity calculations

2.2.3.3 Effective width for deflection calculations

2.3 EFFECTIVE WIDTHS OF UNSTIFFENED ELEMENTS

2.3.1 Uniformly compressed unstiffened elements

2.3.1.1 General

2.3.1.2 Effective width for capacity calculations

2.3.1.3 Effective width for deflection calculations

2.3.2 Unstiffened elements and edge stiffeners with stress gradient

2.3.2.1 General

2.3.2.2 Effective width for capacity calculations

2.3.2.3 Effective width for deflection calculations

2.4 EFFECTIVE WIDTH OF UNIFORMLY COMPRESSED ELEMENTS WITH AN EDGE STIFFENER

2.4.1 General

2.4.2 Effective width for capacity calculations

2.4.3 Effective width for deflection calculations

SECTION 3 MEMBERS

3.1 GENERAL

3.2 MEMBERS SUBJECT TO AXIAL TENSION

3.2.1 Design for axial tension

3.2.2 Nominal section capacity

3.2.3 Distribution of forces

3.2.3.1 End connections providing uniform force distribution

3.2.3.2 End connections providing non-uniform force distribution

3.3 MEMBERS SUBJECT TO BENDING

3.3.1 Bending moment

3.3.2 Nominal section moment capacity

3.3.2.1 General

3.3.2.2 Based on initiation of yielding

3.3.3 Nominal member moment capacity

3.3.3.1 General

3.3.3.2 Members subject to lateral buckling

3.3.3.2.1 Open section members

3.3.3.2.2 Closed box members

3.3.3.3 Members subject to distortional buckling

3.3.3.4 Beams having one flange through-fastened to sheeting

3.3.4 Shear

3.3.4.1 Shear capacity of webs without holes

3.3.5 Combined bending and shear

3.4 CONCENTRICALLY LOADED COMPRESSION MEMBERS

3.4.1 General

3.4.2 Singly-symmetric sections subject to distortional buckling

3.4.3 Columns with one flange through-fastened to sheeting

3.5 COMBINED AXIAL COMPRESSION OR TENSION, AND BENDING

3.5.1 Combined axial compression and bending

3.5.2 Combined axial tension and bending

3.6 CYLINDRICAL TUBULAR MEMBERS

3.6.1 General

3.6.2 Bending

3.6.3 Compression

3.6.4 Combined bending and compression

APPENDIX B METHODS OF ANALYSIS

B3 Second order elastic analysis

(a),(b)

APPENDIX D BUCKLING STRESSES AND MOMENTS AND SHEARS FOR SECTIONS IN COMPRESSION, BENDING AND SHEAR

D1 MEMBERS IN COMPRESSION

D1.1 Global buckling stresses

D1.1.1 Compression members without holes

D1.1.1.1 Sections not subject to torsional or flexural-torsional buckling

D1.1.1.2 Doubly or singly-symmetric sections subject to torsional or flexural-torsional buckling

D1.1.1.3 Point-symmetric sections

D1.1.1.4 Non-symmetric sections

D1.2 Distortional buckling stresses

D1.2.1 Compression members without holes

D1.2.1.1 General channels in compression

D1.2.1.2 Simple lipped channels in compression

D2 MEMBERS IN BENDING

D2.1 Global buckling moments

D2.1.1 Members in bending without holes

D2.1.1.1 General

D2.1.1.2 Singly, doubly and point symmetric sections

D2.1.1.3 Point symmetric Z sections

D2.2 Distortional buckling stresses

D2.2.1 Members in bending without holes

Assumptions

fy and fu are read directly from section properties. No reductions or increases in fy from Clause 1.5.1.2 - Strength increase resulting from cold forming.

Shapes with intermediate stiffeners and stiffened lips are not supported. If they are used then the resulting design or check will be conservative because the effect of the stiffeners will not have been taken into account.

Unlipped (plain) Cee flanges are assumed to be an unstiffened element and the web a stiffened element.

Webs of top hats that have edge stiffened bottom flanges are assumed to be a stiffened element (ie. flanges are assumed to provide sufficient edge support to the web to have the web classified as stiffened).

A ratio of effective section I to gross section I is included in the design report to provide a deflection factor approximating the increase in gross section deflections at the reported design load forces and moments. The SPACE GASS analysis deflections are based on gross sections.

Clause 1.3.39 - a single lateral restraint 'L' not combined with any other flange restraint is not recognised as an effective restraint for a segment as they do not meet the requirements of a partially retrained cross section for a segment.

Clause 1.3.39 - a continuous lateral restraint 'C' is recognised as a restraint and assumed to meet the requirements of a partially restrained cross section for a segment.

Clause 2.1.1 - full section properties and yield strengths read directly from section properties.

Clause 2.1.2.1 - actual shape including bends is used to calculate effective section properties.

Clause 2.1.3.1 - failure if elements exceed prescribed ratios, warning given if elements exceed clause note's ratios.

Clause 2.1.3.3 - shear lag effects not considered. A warning given if group length < 30 * flange width.

Clause 2.2.1.3 - procedure I used, Procedure II not used.

Clause 3.2.3.1 - it is assumed (a) and (b) are satisfied for concentric end connections.

Clause 3.2.3.2 - for channels connected by flanges only, it is assumed b(i) and b(ii) are satisfied.

Clause 3.3.3.2.1(b) - Iyc for zeds taken as geometric axis Iy/2.

Clause 3.3.2.3 - section moment capacity based on inelastic reserve capacity NOT considered.

Clause 3.3.3 - unequal angles, equation D2.1.1.1(4) used for bending in x and y axis.

Clause 3.3.3 - Mo is NOT calculated using a rational flexural-torsional buckling analysis.

Clause 3.3.3.3 - only lipped cee, lipped cee back to back and zed sections considered for distortional buckling .

Clause 3.3.3.2.1(a) - alternative for Z-sections restrained by sheeting against lateral movement NOT considered.

Clause 3.3.3.4 - only (i),(ii),(iii),(iv),(v),(vii)(vii based on group length) requirements are checked, assumed other requirements checked by user.

Clause 3.3.4.1 - no shear buckling check on CHS sections.

Clause 3.3.4 - for top hat sections, shear in x axis carried by top flange and horizontal component of web, shear in y axis carried by vertical component of the web.

Clause 3.4.1 - holes have not been allowed for in the calculation of Ae for Nc.

Clause 3.4.1 - clause notes not applied. User to specify effective lengths in steel member design group properties.

Clause 3.4.2- only lipped single or back to back cee considered for axial compression distortional buckling.

Clause 3.4.2 - fod calculated using Appendix D1.2.

Clause 3.4.3 - s = 0.5 (fastener in center of flange), smallest flange width used for zed sections.

Clause 3.4.3 - only (i),(ii),(iii),(iv),(v),(vi),(ix),(x based on group length) requirements are checked, assumed other requirements checked by user.

Clause 3.5 - equations 3.5.1(2) and 3.5.2(2) are included in section checks. Msx and Msy are used in equation 3.5.1(2)for the section check.

Clause 3.5.1 - equations 3.5.1(1) and 3.5.1(2) are included in member checks, equation 3.5.1(3) is used if N*/phicNc <= 0.15.

Clause 3.5.1 - actual group length used for L in the L/1000 centroid shift for angles.

Clause 3.5.2 - equation 3.5.2(1) is included in member checks only.

Clause 3.5.2 - equation 3.5.2(1) the axial tension term is conservatively ignored (N* is always zero) if axial tension exists.

Clause 3.6.3 - axial compression section capacity for CHS is based on gross area.

Appendix D - for zeds, the widest flange is used determining flange and lip properties.

Appendix D - flange and lip properties represented as square corners and centerlines.

Appendix D1.1.1.2 - alternative equation D1.1.2(8) not considered.

Appendix D1.1.1.2 - equal angles, if no area reduction due to fy, foc based on maximum compressive length and smallest radius of gyration in either axis.

Appendix D2.2.1 - no reduction in lambda for any bracing interval.